Hi,
We played with 4300 but the stencil life was short. I liked the idea of a
no clean water soluble. I really hope to hear what is causing this issue.
Thanks,
Bob Kondner
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Wednesday, January 21, 2009 11:04 AM
To: [log in to unmask]
Subject: Re: [TN] Strange Mask Appearance
Hi Bill!
Yes, I would like your photos, thank-you very much.
To respond to Tan Geok Ang, the flux we used for the rework is Amtech
4300, a solvent-based (ethanol), water washable no-clean. I know the
picture looks like the area around the screw heads is delaminated, but
it is not. The copper is relieved around the holes for the hardware in
the inner planes and that may contribute to the appearance that there's
delamination.
Here's a photo of the same exact place on the same exact board after
doing nothing but heating the PCB up to 125 C. as I described in my
earlier post.
http://stevezeva.homestead.com/files/Mask_Discoloration_After_Heating.jp
g
And the "before" photo:
http://stevezeva.homestead.com/files/Mask_Discoloration.jpg
Pretty dramatic change huh?
Steve
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of [log in to unmask]
Sent: Tuesday, January 20, 2009 1:59 PM
To: [log in to unmask]
Subject: Re: [TN] Strange Mask Appearance
Steve- I'm probably the culprit that put that report on TN long ago- and
again recently. Liquid solder masks often use fumed silica as
filler/thickener to keep it in place. This is often sold under the
Cab-O-Sil tradename.
Aggressive cleaning agents can dissolve off part of the under or un
cured solder mask polymer, exposing the while silica filler. When you
heat the undercured mask, it will soften and allow the filler to sink
down into the polymer, so the solder mask all looks green again.
Re the curing from wave solder, this may not work if you are working
with a UV cured mask. That's why it is important to monitor the output
of UV lamps, which not all shops do, thinking that UV lamps behave the
same as incandescent
lamps- which they don't.
Yes, the heat gun is a very inexpensive $0.05 test, quick, easy and
requires no instrumentation.
(Steve- I have some photos of the differences between one, two and three
passes under UV lamps to show the difference if you'd like them. If so,
pls give me a mailing address.)
Bill Kenyon
Global Centre Consulting
3336 Birmingham Drive
Fort Collins, CO 80526
Tel: 970.207.9586 Cell: 970.980.6373
**************A Good Credit Score is 700 or Above. See yours in just 2
easy steps!
(http://pr.atwola.com/promoclk/100000075x1215855013x1201028747/aol?redir
=http://www.freecreditreport.com/pm/default.aspx?sc=668072%26hmpgID=62%2
6bcd=De
cemailfooterNO62)
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0 To
unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or
(re-start) delivery of Technet send e-mail to [log in to unmask]: SET
Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the
posts: send e-mail to [log in to unmask]: SET Technet Digest Search the
archives of previous posts at: http://listserv.ipc.org/archives Please
visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for
additional information, or contact Keach Sasamori at [log in to unmask] or
847-615-7100 ext.2815
-----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16
for additional information, or contact Keach Sasamori at [log in to unmask] or
847-615-7100 ext.2815
-----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------
|
